A semiconductor laser device (LD) as an optical semiconductor device is heavily used as a light source of an optical communications system, and a light source of information processing equipment. A visible semiconductor laser is used as a light source of the information processing equipment such as a CD player, DVD player, laser printer, POS, bar code reader, document file system, and so forth. A so-called ridge structure is known as one of structures for the semiconductor laser device (the optical semiconductor device) (for example, JP-A No. 218469/2003).
A semiconductor laser apparatus described in JP-A No. 218469/2003 is a nitride-based semiconductor apparatus of a ridge-stripe structure. The semiconductor laser apparatus has a structure wherein an n-type GaN buffer layer, a modulation-doped superlattice n-type cladding layer, an n-type GaN optical waveguide layer, a multiple quantum well active layer, a p-type GaN optical waveguide layer, a modulation-doped superlattice p-type cladding layer, and p-GaN contact layer are caused to undergo multiple-layer growth over an n-type GaN semiconductor substrate. Those multi-layer growth layers are formed by an organometallic chemical vapor deposition method (MOCVD). In forming the multi-layer growth layers, the n-type GaN buffer layer is caused to undergo growth over the n-type GaN semiconductor substrate by the MOCVD. Subsequently, the n-type cladding layer, n-type GaN optical waveguide layer, multiple quantum well active layer, p-type GaN optical waveguide layer, p-type cladding layer, and p-GaN contact layer are caused to undergo sequential growth by the MOCVD.
Further, in order to form a ridge stripe, portions of the multi-layer growth layers, down to halfway through the modulation-doped superlattice p-type cladding layer, are removed by a dry etching method, and an SiO2 insulating film is formed on a surface exposed after such removal as described. Thereafter, an SiO2 insulating film over the p-GaN contact layer that is the uppermost layer of a ridge is partially removed, and a p-side electrode made of Pt is formed in removed portions of the SiO2 insulating film, a p-side electrode pad for wiring, made of Ti/Pt/Au, being further formed in the removed portions.